1. Field of the Invention
The present invention relates to a handlebar gear shifter for pulling or releasing a cable of a bicycle derailleur mechanism.
2. The Related Art
There are various types of bicycle gear shifters available in the market. Whatever automatic or manual gear shifters, the fundamental principle of gear shifting is to pull or release a cable, which connects the gear shifter to a bicycle derailleur mechanism, to change the position of a bicycle chain on a gear assembly for realizing gear shifting. However, for those gear shifters, a rider has to remove his/her hand from the handlebar to the shifting device in case of gearshift, and the removal of the hand could cause an unstable for controlling the bicycle even a falling down. Referring to FIG. 1, which shows a conventional handlebar gear shifter, a rider has no need to remove the hand from the handlebar to the gear shifter when shifting a gear. A cable C of the conventional handlebar gear shifter is directly connected through a cable-guidance A to a recess of a sleeve B. When turning the sleeve B, it thus directly pulls or releases the cable C, which is connected to a bicycle derailleur mechanism, for shifting the gear. However, because the wire-guidance A with a larger curve contacts with the cable C that causes a larger friction drag, a rider has to apply a larger force to shift gear. It is very inconvenient for operation and the cable C is easily broken after many repeated operations.
In view of the above problem, U.S. Pat. No. 6,494,112 B2 filed by the present inventor, discloses a handlebar gear shifter comprising a sleeve rotatably mounted to a handlebar from which a support plate extends. An L-shaped mediate member has an end pivotally connected onto the support plate. A first cable has one end thereof engaged with a recess in the sleeve and the other end of the first cable is engaged with the mediate member. A second cable connects the mediate member and a derailleur mechanism. A C-shaped member having notches is connected to the handlebar. A spring member is engaged with the sleeve. An index member is biased by the spring member and removably engaged with one of the notches. The mediate member is pivoted by rotating the sleeve together with the mediate member to shift the gear. However, the position of the support plate is closer to the center of the handlebar, which interferes with a brake member of a bicycle and is thus inconvenient for operation. Moreover, the sleeve shall be turned a larger angle for each gearshift. It is not so easy for riders to finish all gearshifts at one time. And the numerals of gearshift indication on the handlebar respectively showing each gear are more widely distributed. The riders are hard to read the numerals. The reason is that the distance between a pivot end of the L-shaped mediate member and one distal end thereof connected to the first cable is larger than that between the pivot end and the other distal end thereof connected to the second cable. Thus, the traveling distance of the first cable is larger than that of the second cable for each gearshift. The traveling distance of the first cable shall be larger for finishing each gearshift, so that the numerals of gearshift indication on the handlebar are more widely distributed that is not easy to read for a rider.
The present invention intends to provide with a handlebar gear shifter that solves the above problems.